Preface

Gene manipulation and polymerase chain reaction technologies, which were born in the late 1870s, drastically changed the world of biotechnology. A substantial number of genes have been cloned from various species, and many genome sequences have been determined using these technologies. Moreover, the emergence of cloning technology and the discovery of embryonic stem (ES) cells drastically changed life science research. In the last several decades, the pathology of many diseases was elucidated by testing transgenic animals. The discovery of ES cells leads to the discovery of induced pluripotent stem (iPS) cells, and regenerative medicine using iPS cells is being used in several clinical trials at present. Biotechnology in life science continues to progress on a day-to-day basis.

 With great expectations, the progress of biotechnology has imparted novel and important roles to biochemical engineers. Previously, the main role of biochemical engineers had been to design bioreactors that produced industrially important compounds under optimal conditions. Examples of these new roles for biochemical engineers include application of gene manipulation technology to bioremediation and production of bioenergy and novel chemicals. Moreover, the role has expanded to the medical field where tissue engineering, drug delivery, and therapy have grown drastically.

Based on this background, this book deals with current topics in biochemical engineering. The chapters of this book discuss research that has introduced artificial enzymes, kinetic models in bioprocessing, a small-scale production process, and production of energy with microbial fuel. These chapters offer novel ideas for the production of effective compounds and energy. Moreover, other research has introduced the production technology of stem cells and biomedical processes using nanoshells and extracellular vesicles, which will give important information for regenerative medicine and therapy.

I would like to thank Ms. Sara Petanjek and the publishing managers of InTech Publisher for their support and assistance throughout the writing and publication processes of this book.

> **Naofumi Shiomi** Kobe College, Japan

**1**

**Chapter 1**

*Naofumi Shiomi*

**1. Introduction**

developed.

this book by other authors.

**2. Construction of artificial proteins**

tein). Each step is discussed in the following sections.

Introductory Chapter: Artificial

Until the middle of 1970s, the roles of biochemical engineers had been to design effective processes for production of industrially important proteins and to control bioreactors under optimal conditions. Many microorganisms were isolated from soils, rivers, and seawater, and their genes were randomly disrupted by mutagenic agents such as 1-methyl-3-nitro-1-nitrosoguanidine to enhance the productivity, which was the best procedure of breeding for a long time. Gene manipulation technology born in the late 1870s was a groundbreaking invention, and the technology drastically changed the world of biotechnology. Polymerase chain reaction (PCR) method and genome analysis using high-performance DNA sequencers, which were born after gene manipulation technology, enhanced the drastic progress. Recently, a huge number of genes have been cloned from isolated microorganisms, and many excellent vector plasmids and promoters have been

Recently, the interest of biochemical engineers shifted from breeding using gene manipulation technology to using the discovered novel biocatalysts and the "directed evolution" technology. The idea of directed evolution was proposed by Arnold et al. They proposed that artificial evolution, which is similar to the natural evolution that slowly occurs in the nature world, can be performed at rapid speed using biotechnology. Based on this concept, many studies have been conducted and have become an important target of biochemical engineers. In the future, such artificial proteins will introduce a next wave in the world of biotechnology [1]. Based on this background, I introduce in this chapter the recent advancements in artificial enzymes. There are other important targets for biochemical engineers, and therefore, I recommend referring to other chapters of

The scheme of the screening process of an artificial protein or enzyme using directed evolution technology is shown in **Figure 1**. The screening process in a single cycle is composed of three steps: (1) construction of DNA (or RNA) variants, (2) construction of display library composed of both DNA (or RNA) variants and protein molecules, and (3) screening of target DNA variants. Directed evolution is completed by several repeats of these steps to obtain an optimal enzyme (or pro-

Enzyme Produced by Directed

Evolution Technology
